Access auto declared array

Question

auto messwerte2 = { 3.5, 7.3, 4.9, 8.3, 4.4, 5.3, 3.8, 7.5 };

Which possibilities exist to access a single value explicitly of this array-like looking structure which as I was informed is actually a std::initializer_list ?

I don't know how your loop looks like, and you don't show it, but chances are very much that if you read up on "arrays" you probably will stumble across the right `[]` syntax... and "loop" implies you iterate over individual elements (which implies that it demonstrates how to access a single one...) — Marcus Müller, Oct 11 '16 at 13:45
Why is my question on -4? I had a problem, that came probably from a misunderstanding and confusing an array with a different structure of c++ language. How could I fix this question to be "better"? I mean, I received an answer that was directly focused to clarify my misunderstanding, if somebody else has the same problem this thread should help him, as it helped me. — baxbear, Sep 15 '18 at 15:30

πάντα ῥεῖ · Accepted Answer · 2016-10-11T14:00:10.707

4

Which possibilities exist to access a single value explicitly of this array?

It's not an array, but is deduced to a std::initializer_list<double> which can be accessed through an iterator or a range based loop:

#include <iostream>

auto messwerte2 = { 3.5, 7.3, 4.9, 8.3, 4.4, 5.3, 3.8, 7.5 };

int main() {

    for(auto x : messwerte2) {
        std::cout << x << std::endl;
    }
}

Live Demo

To make it an array use an explicit array declaration:

double messwerte2[] = { 3.5, 7.3, 4.9, 8.3, 4.4, 5.3, 3.8, 7.5 };

edited Oct 11 '16 at 14:00

answered Oct 11 '16 at 13:51

πάντα ῥεῖ

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The OP knows they can use a ranged based for loop. They want to know how to get just a single value from a specific position. – NathanOliver Oct 11 '16 at 13:53
@NathanOliver Yeah I just noticed that. – πάντα ῥεῖ Oct 11 '16 at 13:55
Seems like because an initializer_list cant be used like an array, so seems like it is not possible. Thank you. – baxbear Oct 11 '16 at 13:59
@baxbear Yes. I've added a link to the reference additionally. – πάντα ῥεῖ Oct 11 '16 at 14:00

score 1 · Answer 2 · answered Oct 11 '16 at 13:49

auto messwerte2 = { 3.5, 7.3, 4.9, 8.3, 4.4, 5.3, 3.8, 7.5 };

doesn't declare an array. It declares a std::initializer_list<double>

To declare an array, use:

double messwerte2[] = { 3.5, 7.3, 4.9, 8.3, 4.4, 5.3, 3.8, 7.5 };

Then you can use the regular array indexing syntax.

Access auto declared array

2 Answers2